Biostereometric analysis of the tympanic membrane using photogrammetric techniques will use objective and precise engineering techniques to document important clinical observations which were previously made casually and subjectively. These techniques will also be used simultaneously with tympanometry to provide objective measurement previously unrecorded or incompletely analyzed. The technology to be used has been extensivley developed for commercial, military and space applications. It provides three-dimensional contour maps, volumes, cross-sectional contours, etc. Basic research applications of this technology will be centered on animals modes of eustachian tube dynsunction. Photogrammetric measures will be made in conjunction with impedance audiometry to provide information which will be used to delineate specific contributors to middle ear impedance, i.e., the drum vs. the ossicular ligaments vs. the cochlea. It will also be used to correct for change in cavity size during tympanometry in order to more accurately measure middle ear pressures, and also to correct for resonance affects that changes in cavity size cause at higher frequencies than those commonly used clinically. Similar measurements will be made in a clinical population. In addition, clinical research using the photogrammetric measurements will be aimed at the follwoing characteristics: (1) definition and documentation of curvature and volume displacement of the tympanic membrane in normal and in diseased human ears; (2) assessment of the contribution of the tympanic membrane to the transformer ratio of the ear according to the Helmholz-Tonndorf theory based on a curved lever principle; (3) documentation in the change of shape during chronic eustachian tube dysfunction and negative middle ear pressure with evaluation of the hysteresis of the elastic properties of the tympanic membrane; and (4) evaluation in changes of migration patterns of squamous epithelium along the tympanic membrane in normal and diseased ears.